Contactless multispectral biometric capture

ABSTRACT

A number of biometric systems and methods are disclosed. A system according to one embodiment includes an illumination subsystem, an imaging subsystem, and an analyzer. The illumination subsystem is disposed to illuminate a target space. The imaging subsystem is configured to image the target space under distinct optical conditions. The analyzer is provided in communication with the illumination subsystem, the imaging subsystem, and the three-dimensional subsystem. The analyzer also has instructions to operate the subsystems to collect substantially simultaneously a plurality of images of the object disposed at the predetermined spatial location under multispectral conditions.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a non-provisional, and claims the benefit, ofcommonly assigned U.S. Provisional Application No. 60/943,207, filedJun. 11, 2007, entitled “Contactless Multispectral Biometric Capture,”the entirety of which is herein incorporated by reference for allpurposes.

This application is a continuation-in-part of U.S. patent applicationSer. No. 12/100,597, filed Apr. 10, 2008, entitled “Biometric DetectionUsing Spatial, Temporal, And/Or Spectral Techniques,” which is anonprovisional, and claims the benefit, of U.S. Provisional PatentApplication No. 60/911,007, filed Apr. 10, 2007, entitled “Spatial AndTemporal Biometric Detection,” the entire disclosure of each of which isincorporated herein by reference for all purposes.

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/779,998, filed Jul. 19, 2007, entitled “MultibiometricMultispectral Imager,” which is a nonprovisional, and claims thebenefit, of U.S. Provisional Patent Application No. 60/832,233, filedJul. 19, 2006, entitled “Whole-Hand Multispectral Imager,” the entiredisclosure of each of which is incorporated herein by reference for allpurposes.

BACKGROUND

This application relates to biometrics. More specifically, thisapplication relates to methods and systems for using a various biometricsensor.

“Biometrics” refers generally to the statistical analysis ofcharacteristics of living bodies. One category of biometrics includes“biometric identification,” which commonly operates under one of twomodes to provide automatic identification of people or to verifypurported identities of people. Biometric sensing technologies measurethe physical features or behavioral characteristics of a person andcompare those features to similar prerecorded measurements to determinewhether there is a match. Physical features that are commonly used forbiometric identification include faces, irises, hand geometry, veinstructure, and fingerprint patterns, which is the most prevalent of allbiometric-identification features. Current methods for analyzingcollected fingerprints include optical, capacitive, radio-frequency,thermal, ultrasonic, and several other less common techniques.

Most existing fingerprint sensors rely on relatively high-qualitycontact between the finger and the sensor to obtain images. Obtainingadequate contact is both finicky and time-consuming because of factorsrelated to individual characteristics of users of the sensors, thequality of the skin, and environmental variability. For some individualsand under some circumstances, achieving adequate contact is impossible.Ease of consistent fingerprint capture limits the effectiveness andscope of applications that utilize fingerprint biometrics for identitymanagement. Furthermore, in some cultures and during specific publichealth events, there is a negative perception of contact-basedfingerprinting. This was the case, for instance, during the SARSoutbreak in 2003.

Contact measurement is a fundamental requirement for many forms offingerprint acquisition, such as optical total internal reflectance, RF,capacitance, thermal, and ultrasound techniques. There have been a smallnumber of fingerprint sensors that have been developed and marketed as“noncontact” fingerprint sensors. In many cases, these sensors use apedestal or some other device to locate and stabilize the finger. Thus,although the fingerprint region is not in contact with the sensor, otherportions of the finger are contacting the sensor, which compromises theadvantages that a true noncontact fingerprint sensor would embody.

Most existing fingerprint sensors are also susceptible to being defeatedthrough the use of artificial or altered fingerprint samples. Althougheach fingerprint technology may be susceptible to only specific types ofartificial (or “spoof”) samples, the effort required to spoof mostsystems is fairly modest one the “trick” for doing so is known.

BRIEF SUMMARY

A biometric system is disclosed according to some embodiments. Thebiometric system includes one or more illumination sources, a firstimager, a second imager and an analyzer. The one or more illuminationsources may be configured to illuminate at least a portion of a targetspace. The target space may be located within free space, in someembodiments, and/or defined partially be a platen or other mechanicaldevice, in other embodiments. In other embodiments, the target space isconfigured to receive a human hand. The first imager may be configuredto receive light from at least a portion of the target space under afirst optical condition. The second imager may be configured to receivelight from at least a portion of the target space under a second opticalcondition. The first optical condition is distinct from the secondoptical condition. The analyzer may be communicatively coupled with theone or more illumination sources and the plurality of imagers. Theanalyzer may also be configured to control the operation of the one ormore illumination sources, the first imager, and the second imager inorder to produce a multispectral image of an object placed within thetarget space from the light received at first imager and the secondimager. The first imager and the second imager may be controlled by theanalyzer, in one embodiment, to imager the target space substantiallysimultaneously.

In various embodiments, the first imager is configured to receive lightfrom a first subspace of the target space and the second imager isconfigured to receive light from a second subspace of the target space.In other embodiments, the first imager is focused at a first focal planeand the second imager is focused at a second focal plane, wherein thefirst focal plane and the second focal plane are distinct. In otherembodiments, the biometric system may include a first processor coupledwith the first imager and a second processor coupled with the secondimager. In other embodiments, the biometric system includes a userinterface configured to substantially indicate at least a portion of thetarget space to a user. In other embodiments, the biometric systemincludes a presence detector and/or proximity detector configured todetect the presence of an object within the target space and/or theproximity of an object relative to the target space.

A method for collecting a multispectral biometric image is disclosedaccording to various embodiments. At least a portion of a target spaceis illuminated. The illumination may include various illuminationtechniques, illumination conditions, and/or illumination sources. Lightis received from at least a portion of the target space under a firstoptical condition. Light is also separately received from at least aportion of the target space under a second optical conditionsubstantially simultaneously as light is received from the target spaceunder the first optical condition. The first optical condition and thesecond optical condition, in some embodiments, are distinct. Amultispectral image of an object within the target space may be derivedfrom the light received under either or both of the first opticalcondition and the second optical condition.

In some embodiments, an indication of at least a portion of the targetspace is provided. In other embodiments the presence of an object withinthe target space is detected. In other embodiments, the first opticalcondition and the second optical condition are selected from the groupconsisting of polarized light, total internally reflected light, lightwith a specific wavelength, light within a specific wavelength band,light from a subspace within the target space, and/or light from a focalplane within the target space. In other embodiments, a first imagerprovides a first image of at least a portion of the target space underthe first optical condition and a second imager provides a second imageof at least a portion of the target space under the second opticalcondition. In another embodiment, the first image has a resolutiongreater than the resolution of the second image.

Another biometric system is disclosed according to various embodiments.An illumination means for illuminating a target space is included. Afirst imaging means for imaging at least a portion of the target spaceunder a first optical condition and providing a first image may also beincluded. A second imaging means for imaging at least a portion of thetarget space under a second optical condition distinct from the firstoptical condition and providing a second image may also be provided. Aprocessing means for controlling the illumination means, the firstimaging means and the second imaging means is also provided. Theprocessing means may be configured to derive a multispectral image fromthe first image and the second image.

Presence sensing means may also be included in some embodiments, forsensing the presence of an object within at least a portion of thetarget space. In other embodiment the first optical condition and thesecond optical condition may be selected from the group consisting ofpolarized light, total internally reflected light, light with a specificwavelength, light within a specific wavelength band, light from asubspace within the target space, and/or light from a focal plane withinthe target space. In yet other embodiments an indication means forindicating at least a portion of the target space to a user is included.

A whole-hand biometric sensor is also provided according to variousembodiments. The whole-hand biometric sensor includes a platen, one ormore illumination sources, a first imager, a second imager and ananalyzer. The platen may be configured to receive a human hand and/orinclude a surface that defines a target surface. The one or moreillumination sources may be configured to illuminate at least a portionof the target surface. The first imager may be configured to receivelight from at least a portion of the target surface under a firstoptical condition. The second imager may be configured to receive lightfrom at least a portion of the target surface under a second opticalcondition. The first optical condition may be distinct from the secondoptical condition. The analyzer may be communicatively coupled with theone or more illumination sources and the plurality of imagers. Theanalyzer may also be configured to control the operation of the one ormore illumination sources, the first imager, and the second imager inorder to produce a multispectral image of an object placed on the targetsurface from the light received at first imager and the second imager.

In various other embodiments, the analyzer may be configured to controlthe first imager and the second imager to provide images substantiallysimultaneously. In other embodiments, the first imager may be configuredto image a first spatial location on the target surface and the secondimager may be configured to image a distinct second spatial location onthe target surface. Either or both of the first imager and the secondimager may include one or more optical elements selected from the listconsisting of a color filter, a color filter array, a linear polarizer,a circular polarizer, a diffuser, a collimator, a gratings, and a lens.The first imager may be focused at a first focal plane and the secondimager may be focused at a second distinct focal plane. Otherembodiments include a first processor coupled with the first imager anda second processor coupled with the second imager. A user interfaceconfigured to substantially indicate at least a portion of the targetspace to a user may also be included according to various otherembodiments. A presence and/or proximity detector configured to detectthe presence and/or proximity of an object within and/or relative to thetarget space.

A method for collecting a multispectral biometric image of a human handis also disclosed according to various embodiments. At least a portionof a target surface of a platen is illuminated with one or more lightsources of various types and/or configurations. Light may be receivedfrom at least a portion of the target surface under a first opticalcondition. Light may be separately received from at least a portion ofthe target surface under a second optical condition substantiallysimultaneously as the light is received the target surface under a firstoptical condition. The first optical condition and the second opticalcondition may be distinct. A multispectral image of an object within thetarget surface may be derived from the light received under either orboth of the first optical condition and the second optical condition.

In various embodiments the first optical condition and the secondoptical condition may be selected from the group consisting polarizedlight, total internally reflected light, light with specific wavelength,light within a specific wavelength band, light from a first subspacewithin the target space, and/or light from a first focal plane withinthe target space. In some embodiments the first imager provides a firstimage of at least a portion of the target space under the first opticalcondition and/or the second imager provides a second image of at least aportion of the target space under the second optical condition. In otherembodiments the first image has a resolution greater than the resolutionof the second image.

Another biometric system is disclosed according to various embodimentsthat includes illumination means for illuminating a target space, afirst imaging means, a second imaging means and processing means. Thefirst imaging means adapted for imaging at least a portion of the targetspace under a first optical condition and providing a first image. Thesecond imaging means adapted for imaging at least a portion of thetarget space under a second optical condition distinct from the firstoptical condition and providing a second image. The processing meansadapted for controlling the illumination means, the first imaging meansand the second imaging means. The processing means may be configured toderive a multispectral image from the first image and the second image.Presence sensing means for sensing the presence of an object within atleast a portion of the target space may also be included in variousembodiments. In other embodiments, the first optical condition and thesecond optical may be selected from the group consisting polarizedlight, total internally reflected light, light with specific wavelength,light within a specific wavelength band, light from a first subspacewithin the target space, and/or light from a first focal plane withinthe target space.

A biometric system is disclosed according to one embodiment thatincludes one or more illumination sources, a plurality of imagers and ananalyzer. The one or more illumination sources are configured toilluminate a target space, wherein the target space is located in freespace or relative to a platen. The plurality of imagers are configuredto receive light from the target space under multispectral conditions.Each imager is configured to receive light from the target space underdifferent multispectral conditions. The different multispectralconditions may include differences in illumination wavelength orwavelengths, differences in imaging wavelength or wavelengths,differences in illumination angle, differences in imaging angle,differences in imaging resolution, differences in spatial coverage,and/or differences in focal plane. The analyzer may be communicativelycoupled with the one or more illumination sources and the plurality ofimagers. The analyzer may also be configured to control the operation ofthe one or more illumination sources and/or the plurality of imagers inorder to produce one or more multispectral image of an object placedwithin the target space from the light received at any or all theimagers. The system may also include a plurality of processors, suchthat each imager is coupled with a processor.

A biometric system is disclosed according to one embodiment thatincludes one or more illumination sources, a first and a second imager,and an analyzer. The one or more illumination sources may be configuredto illuminate a target space. The first imager receives light from afirst subspace of said target space under a multispectral condition. Thesecond imager receives light from a second subspace of said target spaceunder a different multispectral condition. The first imager and thesecond imager receive light substantially simultaneously. The analyzermay be communicatively coupled with the one or more illuminationsources, the first imager, and the second imager. The analyzer may beconfigured to control the operation of the one or more illuminationsources, the first imager, and the second imager in order to derive amultispectral image of an object placed within the target space fromlight received at either or both of the first imager and the secondimager.

A method for collecting a biometric image is provided according toanother embodiment. A target space is illuminated with one or moreillumination sources. Light is received from a first subspace of saidtarget space with a first imager. Light is received from a secondsubspace of said target space with a second imager. A multispectralimage is derived with at least a portion of an object within said targetspace from the light received at either or both of the first imager andthe second imager.

A biometric system is disclosed according to one embodiment. Thebiometric system includes a platen, one or more illumination sources, afirst imager, a second imager and an analyzer. The platen may be adaptedfor placement of a purported skin site by an individual. The one or moreillumination sources may be configured to illuminate the skin site. Thefirst imager may be configured to receive light from a first zone ofsaid skin site under a multispectral conditions. The second imagerconfigured to receive light from a second zone of said skin site underanother multispectral conditions. The analyzer may be communicativelycoupled with the one or more illumination sources, the first imager, andthe second imager. The analyzer may be configured to control theoperation of the one or more illumination sources, the first imager, andthe second imager in order to derive a multispectral image of the skinsite from light received at either or both of the first imager and thesecond imager.

A biometric system is disclosed according to another embodiment, thatincludes one or more illumination sources, a plurality of imagers and ananalyzer. The one or more illumination sources may be configured toilluminate a target space. The plurality of imagers may be configured toreceive light from the target space under multispectral conditions. Atleast one imager receives light with a multispectral condition distinctfrom the multispectral condition received with at least one otherimager. The analyzer may be communicatively coupled with the one or moreillumination sources and the plurality of imagers. The analyzer may beconfigured to control the operation of the one or more illuminationsources and the plurality of imagers in order to produce a multispectralimage of an object placed within the target space from the lightreceived at any or all the imagers.

A biometric system is disclosed according to one embodiment, thatincludes one or more illumination sources, a first imager, a secondimager, and an analyzer. The one or more illumination sources may beconfigured to illuminate a target space. The first imager may beconfigured to receive light from said target space under a first opticalcondition. The second imager may be configured to receive light fromsaid target space under a second optical condition. The analyzer may becommunicatively coupled with the one or more illumination sources, thefirst imager, and the second imager. The analyzer may be configured tocontrol the operation of the one or more illumination sources, the firstimager, and the second imager in order to derive a multispectral imageof an object placed within the target space from light received ateither or both of the first imager and the second imager.

A method for collecting a biometric image is disclosed according toanother embodiment. A target space is illuminated. Light is receivedfrom the target space under a first optical condition. Light is receivedfrom the target space under a second optical condition. A multispectralimage of an object within said target space is derived from the lightreceived under the first optical condition and/or the second opticalcondition. The first and/or second optical condition may includeillumination wavelength or wavelengths, imaging wavelength orwavelengths, illumination angle, imaging angle, imaging resolution,spatial coverage, and/or focal plane.

A contactless biometric system is provided according to one embodiment.The contactless biometric system may include one or more illuminationsources, one or more imagers and an analyzer. The one or moreillumination sources may be configured to illuminate a target spacelocated in free space. The one or more imagers may be configured tocollect light from at least a portion of the target space underdifferent multispectral conditions. The analyzer may be configured tocommunicatively coupled with the one or more illumination sources andthe one or more imagers. The analyzer may be configured to control theoperation of the one or more illumination sources and the one or moreimagers in order to derive a multispectral image of an object placedwithin the target space and imaged by the one or more imagers.

A method for collecting a biometric image is provided according toanother embodiment. The presence of an object is detected within atarget space located in free space. The object is illuminated within thetarget space with one or more illumination sources. Light is receivedfrom the target space at one or more imagers with different opticalconditions. A multispectral image of the object within said target spaceis derived from the light received at the one or more imagers.

A contactless biometric system is provided according to anotherembodiment that includes an illumination subsystem, an imagingsubsystem, sensing means, and an analyzer. The illumination subsystemmay be disposed to illuminate a predetermined spatial location in freespace. The imaging subsystem may be disposed to collect light emanatingfrom the predetermined spatial location. The sensing means may beconfigured to sense when a purported skin site is placed substantiallywithin the predetermined spatial location. The analyzer may be incommunication with the illumination subsystem, the imaging subsystem,and the sensing subsystem. The analyzer may comprises instructions tooperate the illumination subsystem, the imaging subsystem, and thesensing subsystem to derive a multispectral image of an object placedwithin the target space and imaged by the one or more imagers.

A method for collecting a biometric image is provided according to oneembodiment. An indication of the proximate location of a target space infree space is provided. An object within the target space is illuminatedwith one or more illumination sources. Light from the target space isreceived at one or more imagers under multispectral conditions and/ordifferent optical conditions. A multispectral image of the object withinsaid target space may be derived from the light received at the one ormore imagers.

A biometric system is disclosed according to another embodiment thatincludes conveying means, illuminating means, imaging means, and logicmeans. The conveying means for conveying an indication of the proximatelocation of a target space in free space. The illuminating means forilluminating at least a portion of the target space. The imaging meansfor receiving light from the target space under multispectralconditions. The logic means for deriving a multispectral image of anobject within said target space from the light received by the imagingmeans.

A biometric system is disclosed according to one embodiment thatincludes a platen, one or more illumination sources, a first imager, asecond imager and an analyzer. The platen may be configured to receive ahuman hand. The one or more illumination sources may be configured toilluminate a hand placed on the platen. The first imager may beconfigured to receive light from a first portion of the hand undermultispectral conditions. The second imager may be configured to receivelight from a second portion of the hand under multispectral conditions.The an analyzer may be communicatively coupled with the one or moreillumination sources, the first imager, and the second imager. Theanalyzer may be configured to control the operation of the one or moreillumination sources, the first imager, and the second imager in orderto derive a multispectral image of the first portion of the hand fromlight received at first imager and derive a multispectral image of thesecond portion of the hand from light received at second imager. Inanother embodiment, a single multispectral image may be derived at theanalyzer from the light received at both the first and second imagers.

A biometric system is disclosed according to one embodiment, thatincludes one or more illumination sources, a plurality of images, and ananalyzer. The one or more illumination sources may be configured toilluminate a hand placed substantially within target space in freespace. The plurality of imagers may be configured to receive light fromportions of a hand placed substantially within the target space undermultispectral conditions. The analyzer may be communicatively coupledwith the one or more illumination sources and the plurality of imagers.The analyzer may be configured to control the operation of the one ormore illumination sources and the plurality of imagers in order toderive a multispectral image of the portions of the hand from lightreceived at the plurality of imagers.

A method for collecting a biometric image of a hand is also providedaccording to one embodiment. A target space located in free space isprovided for the placement of a human hand by an individual. A handwithin the target space may be illuminated using one or moreillumination sources. Light from the hand may be received undermultispectral conditions using one or more imagers. At least onemultispectral image of at least one portion of the hand within thetarget space is derived from the received light.

Embodiments provide a contactless biometric system. The system comprisesan illumination subsystem, an imaging subsystem, a three-dimensionalsensing subsystem, and an analyzer. The illumination subsystem isdisposed to illuminate a predetermined spatial location in free space.The imaging subsystem is disposed to collect light emanating from thepredetermined spatial location. The three-dimensional sensing subsystemis configured to sense when an object is substantially in thepredetermined spatial location. The analyzer is provided incommunication with the illumination subsystem, the imaging subsystem,and the three-dimensional subsystem. The analyzer comprises instructionsto operate the subsystems to collect substantially simultaneously aplurality of images of the object disposed at the predetermined spatiallocation under multispectral conditions.

In some embodiments, the illumination subsystem comprises alight-emitting diode. In some cases, the light-emitting diode maycomprise a white-light emitting diode. In some embodiments, theillumination subsystem comprises multiple light-emitting diodes. In somecases a plurality of light emitting diodes may emit light that issubstantially monochromatic. Such a plurality of light-emitting diodesmay comprise light-emitting diodes with substantially differentwavelength characteristics. A polarizer may also be disposed to polarizelight emanating from the light-emitting diode.

The imaging subsystem may comprise a plurality of imagers oriented andfocused on the predetermined spatial location. Optical filters may bedisposed to filter the wavelengths of light collected by at least one ofthe plurality of imagers. At least one of the plurality of imagers mayincorporate a color filter array. A polarizer may be disposed topolarize light collected by at least one of the plurality of imagers.

The three-dimensional sensing subsystem may comprise a plurality ofcoherent illuminators that are oriented to overlap at the predeterminedspatial location.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages may be realized byreference to the remaining portions of the specification and thedrawings, wherein like reference labels are used throughout the severaldrawings to refer to similar components.

FIG. 1 illustrates a structure that may be used for a contactlessbiometric sensor in one embodiment.

FIG. 2 illustrates a modular biometric sensor according to oneembodiment.

FIGS. 3A, 3B, 3C and 3D illustrate various views of a modular biometricsensor apparatus according to one embodiment.

FIGS. 4A, 4B, 4C and 4D illustrate various views of a spatially modularbiometric sensor apparatus according to one embodiment.

FIG. 5 shows a block diagram of a biometric sensor system according toone embodiment.

FIGS. 6A, 6B, 6C and 6D illustrate various views of a multispectrallymodular biometric sensor apparatus according to one embodiment.

FIGS. 7A, 7B, 7C and 7D illustrate various views of a contactlessbiometric sensor apparatus according to one embodiment.

FIGS. 8A, 8B, 8C and 8D illustrate various views of a multispectrallymodular, contactless biometric sensor apparatus with imagers that focuson different imaging planes according to one embodiment.

FIGS. 9A, 9B, 9C and 9D illustrate various views of a spatially modular,contactless biometric sensor apparatus with imagers that focus ondifferent imaging planes according to one embodiment.

FIG. 10A illustrates a multispectral datacube of a finger generated inaccordance with various embodiments.

FIG. 10B illustrates four overlapping images of a finger from fourspatially modular imagers according to one embodiment.

FIG. 10C separately illustrates the four overlapping images in FIG. 10B.

FIGS. 11A, 11B, 11C and 11D illustrate various views of a spatiallymodular biometric hand sensor apparatus according to one embodiment.

FIG. 12 shows a block diagram of a biometric hand sensor systemaccording to one embodiment.

FIGS. 13A, 13B, 13C and 13D illustrate various views of amultispectrally and/or spatially modular contactless biometric sensorapparatus according to one embodiment.

FIGS. 14A, 14B, 14C and 14D illustrate various views of a spatially andmultispectrally modular, contactless biometric sensor apparatusaccording to one embodiment.

FIGS. 15A, 15B, 15C and 15D illustrate various views of a spatiallyand/or multispectrally modular, contactless biometric sensor apparatuswith imagers that focus on different imaging planes according to oneembodiment.

FIG. 16 shows a contactless biometric system user interface with aholographic image of a hand according to one embodiment.

FIG. 17 shows a contactless biometric system user interface with a lightarray according to one embodiment.

FIG. 18 shows an image of a hand with five zones imaged with a spatiallymodular imagines system according to one embodiment.

FIG. 19 illustrates a multispectral datacube of a hand generated inaccordance with various embodiments.

FIG. 20 illustrates six overlapping images of a hand from four spatiallymodular imagers according to one embodiment.

FIG. 21 separately illustrates the six overlapping images in FIG. 20.

FIG. 22 shows a flowchart of a biometric detection using variousembodiments described herein.

FIG. 23 shows an image of a finger with a tattoo-like feature accordingto one embodiment.

FIG. 24 shows an image of a hand with a number of moles and a scaraccording to another embodiment.

DETAILED DESCRIPTION

A detailed description is provided below of examples of multispectralsystems that may accordingly be used in embodiments, but such adescription is not intended to be limiting since other techniques may beused in alternative embodiments.

Overview

Embodiments disclosed herein provide methods and systems that allow forthe collection and processing of biometric measurements. These biometricmeasurements may provide strong assurance of a person's identity, aswell as of the authenticity of the biometric sample being taken. Suchembodiments, for example, may be incorporated within a number ofdifferent types of devices, such as cellular telephones, personaldigital assistants, laptop computers, and other portable electronicdevices, as well as stand-alone devices for physical or logical access.The common characteristic of the methods and systems is the applicationof multiple distinct optical configurations used to collect a pluralityof image data during a single illumination session, often the images arecollected simultaneously. In some embodiments, the images are collectedof a finger or a hand with or without a platen. In some instances,methods and systems are provided for the collection and processing ofdata using a sensor with two or more distinct imagers. In otherinstances, the methods and systems disclosed pertain to data collectedusing a sensor with a single camera or multiple cameras. Otherembodiments methods and systems are provided for spatially andmultispectrally modular imaging and imaging systems.

The sensors may provide for an information-rich dataset that results inincreased security and usability relative to conventional sensors. Theincreased security derives from combining information from multipleimages that represent distinct optical characteristics of the materialbeing measured. These characteristics provide sufficient information tobe able to distinguish between living human skin and various artificialmaterials and methods that might be used to attempt to spoof the sensor.As well, increased security is derived from the aspect that provides amechanism to perform measurements across a wide range of environmentaland physiological effects. The robust and reliable sampling means thatsystem security standards do not have to be relaxed to compensate forpoor image quality.

Enhanced sensor usability is achieved by reducing the constraints on theindividual for precise contact and/or positioning, as well as therequirement that the individual's skin has particular qualities.Moreover, embodiments also rely on contactless systems. As well, theability to extract subsurface biometric information from imagescollected under certain optical conditions provides a mechanism forperforming biometric determinations even in those cases where thesurface features are missing or damaged. In this way, the multispectralmeasurements made in embodiments are advantageously robust to non-idealskin qualities, such as dryness, excess wetness, lack of resilience,and/or worn features such as are typically associated with the elderly,those who perform significant manual labor, or those whose skin isexposed to chemicals, such as hairdressers or nurses.

The set of all images collected under a plurality of distinct opticalconditions and/or during a single illumination session is referred toherein as “multispectral data.” The different optical conditions mayinclude differences in polarization conditions, differences inillumination angle, differences in imaging angle, differences in colorfilter array characteristics, differences in resolution, differences infocal planes, differences in spatial coverage, and/or differences inillumination wavelength or wavelengths. In some optical conditions theresulting images are significantly affected by the presence anddistribution of TIR phenomena at the interface between the sample and aplaten. These images are referred to herein as “TIR images.” In someoptical conditions, the resulting images are substantially unaffected bythe presence or absence of TIR effects at a platen. These images arereferred to herein as “direct images.” Some embodiments provide imagesthat are taken without a platen, support (for example, the supportdescribed in U.S. Pat. No. 6,404,904), contact point, mechanicalpositioning device, mechanical alignment device, prop, etc. These imagesare referred to herein as “contactless images.” Contactless images arecreated without physical contact between the skin site and the imagingdevice, biometric sensor, and/or any accessory thereof.

Skin sites applicable to the multispectral measurements described hereininclude all surfaces and all joints of the fingers and thumbs, thefingernails and nail beds, the palms, the front of a hand or hands, theback of a hand or hands, the wrists and forearms, the face, the eyes,the ears, and all other external surfaces of the body. While thediscussion below sometimes makes specific reference to “fingers” or“hands” in providing examples of specific embodiments, it should beunderstood that these embodiments are merely exemplary and that otherembodiments may use skin sites at other body parts.

In some embodiments, a sensor provides a plurality of discretewavelengths of light that penetrate the surface of the skin, and scatterwithin the skin and/or underlying tissue. As used herein, reference to“discrete wavelengths” is intended to refer to sets of wavelengths orwavelength bands that are treated as single binned units—for each binnedunit, information is extracted only from the binned unit as a whole, andnot from individual wavelength subsets of the binned unit. In somecases, the binned units may be discontinuous so that when a plurality ofdiscrete wavelengths are provided, some wavelength between any pair ofthe wavelengths or wavelength bands is not provided, but this is notrequired. In some instances, the wavelengths are within theultraviolet—visible—near-infrared wavelength range.

A portion of the light scattered by the skin and/or underlying tissueexits the skin and is used to form an image of the structure of thetissue at or below the surface of the skin. In some embodiments, such animage may include a fingerprint and/or hand image, where the term“fingerprint” is used broadly herein to refer to any representation ofany skin site with dermatoglyphic features.

FIG. 1 shows an example of contactless modular biometric sensor 100according embodiments. The biometric sensor 100 includes a plurality ofimagers 130 are arranged around a single light source 120 and positionsensors 108. A hand 116 placed with a predefined target space locatedabove the biometric sensor 100 may be imaged using the plurality ofimagers 104. The position of the hand relative to the biometric sensor100 may be monitored using the position sensors 108. The positionsensors 108 may include stereoscopic light sources, for example laserLEDs, that illuminate the free space, including the target space, abovethe biometric sensor 100. For example, in conjunction with one or moreimagers 104, stereoscopic light sources may provide an indication whenthe hand is within the target space. The target space may include avolume within free space where an object is substantially in focus atleast one imager when the object placed therein. Thus, a target space,in some embodiments, may depend on the characteristics of the imager(s).In one embodiment, an imager may be positioned to image differentspatial areas of the hand. In another embodiment, an imager may bepositioned to image the same portion of the hand but under differentmultispectral conditions. In another embodiment, an imager may bepositioned to image different focal planes. In another embodiment, animager may image at substantially the same time. The resultant imagesmay be combined using any function to derive a multispectral image.

Spatially Modular Finger Sensor

Various embodiments provide for a spatially modular biometric sensingsystem. As noted above, a multispectral image can be derived from imageswith different spatial coverage. That is, spatially modular imagers maybe used to derive a multispectral image. FIG. 2 shows a spatiallymodular biometric system according to one embodiment. The systemincludes two imagers 230. The imagers 230A and 230B may be separated orcombined on a single circuit board, for example, as conjoinedwafer-level cameras. Each imager may also include various opticalelements 235. While three optical elements 235 are shown, any numberincluding zero may be used. At least one illumination source 220 may beused. In this embodiment, two LEDs 220 are used to illuminate the finger205 on the platen 210. The first imager 230A may receive light from afirst portion of the finger 205. The second imager 230B may receivelight from a second portion of the finger 205 placed on the platen 210.The first portion and the second portion may overlap or be completelydistinct.

FIGS. 3A, 3B, 3C and 3D illustrate various views of another modularbiometric sensor apparatus according to one embodiment. The modularsensor apparatus includes four imagers 330, optical elements 335, andfour light sources 320. While four light sources are shown, any numberof light sources may be used. For example, a single white light sourcemay be used. Each imager 330 receive light from four subsections of thetarget area. These subsections may overlap or be distinct. As shown, afinger 205 is placed on the target surface 212 of a platen 210. Eachimager may image four different parts of the finger. The imagers 330 mayimage each subsection substantially simultaneously.

FIGS. 4A, 4B, 4C and 4D illustrate various views of a spatially modularbiometric sensor apparatus according to another embodiment. Four imagingsubsections 450 are shown in FIGS. 4B, 4C and 4D. Some overlap betweenthe subsections is shown in this embodiment. Subsections without anoverlap may also be used according to another embodiment. Such a systemmay produce four images, like those shown in FIGS. 10A, 10B and 10C.

FIG. 5 shows a block diagram of a biometric sensor system 500 includinga computational device and peripheral devices according to oneembodiment. The figure broadly illustrates how individual systemelements may be implemented in a separated or more integrated manner.Moreover, the drawing also illustrates how each of the four imagers 510may include a dedicated processor 515 and/or dedicated memory 520. Eachdedicated memory 520 may include operational programs, data processingprograms, and/or image processing programs operable on the dedicatedprocessors 515. For example, the dedicated memory 520 may includeprograms that control the dedicated imager 510 and/or provide imageprocessing. The computational device 502 is shown comprised of hardwareelements that are electrically coupled via bus 530. The bus 530,depending on the configuration, may also be coupled with the one or moreLED(s) 505, a proximity sensor (or presence sensor) 512 and four imagingsubsystems 504 according to various embodiments. In another embodiment,imager memory 520 may be shared amongst imagers 515 and/or with thecomputational device 502.

In such embodiments, an imaging subsystem may include an imager 510, aprocessor 515, and memory 520. In other embodiments, an imagingsubsystem 504 may also include light sources and/or optical elements.Imaging subsystems 504 may be modular and additional imaging subsystemsmay be easily added to the system Thus, biometric sensor subsystems mayinclude any number of imaging subsystems 504. The various imagingsubsystems, in one embodiment, may be spatially modular in that eachimaging subsystem is used to image a different spatial location. Thevarious imaging subsystems, in another embodiment, may bemultispectrally modular in that each imaging subsystem is used to imagea different multispectral condition. Accordingly, in such an embodiment,an imaging subsystem 504 may also include various optical elements suchas, for example, color filter arrays, color filters, polarizers, etc.,and/or the imager 510 may be placed at various angles relative to theimaging location. The various imaging subsystems, in another embodiment,may provide focus modularity in that each imaging subsystem is used toimage a different focal point or focal plane.

The hardware elements may include a central processing unit (CPU) 550,an input/output device(s) 535, a storage device 555, a computer-readablestorage 540, a network interface card (NIC) 545, a processingacceleration unit 548 such as a DSP or special-purpose processor, and amemory 560. The computer-readable storage 540 may include acomputer-readable storage medium and a computer readable medium reader,the combination comprehensively representing remote, local, fixed,and/or removable storage devices plus storage media for temporarilyand/or more permanently containing computer-readable information. TheNIC 545 may comprise a wired, wireless, modem, and/or other type ofinterfacing connection and permits data to be exchanged with externaldevices.

The biometric sensor system 500 may also comprises software elements,shown as being currently located within working memory 560, including anoperating system 565 and other programs and/or code 570, such as aprogram or programs designed to implement methods described herein. Itwill be apparent to those skilled in the art that substantial variationsmay be used in accordance with specific requirements. For example,customized hardware might also be used and/or particular elements mightbe implemented in hardware, software (including portable software, suchas applets), or both. Further, connection to other computing devicessuch as network input/output devices may be employed.

Multispectrally Modular Finger Sensor

FIGS. 6A, 6B, 6C and 6D illustrate various views of a multispectrallymodular biometric sensor apparatus according to one embodiment. As shownin this embodiment, each of the four imagers 630, in conjunction withoptional optical elements 635, image most, if not all of the target area212 where the finger 205 is located on the platen 210. The imagers 630may image the target area 212 substantially simultaneously. The imagers630, in this embodiment, may record images under various multispectralconditions, such as, for example, distinct polarization, distinctimaging angle, distinct wavelength or wavelengths, TIR conditions,distinct resolution, distinct focal planes, distinct spatial coverage,color filter array filtering, etc. For example, a first imager 630A maybe associated with a linear polarizing optical element 635A. A secondimager 630B may be a high resolution imager 635B that images, forexample, with a resolution greater than 200 dots per inch. A thirdimager 630C may be associated with a Bayer filter as an optical element635C. A fourth imager may be associated with a blue color filter opticalelement 635D. While the imagers 630 and the associated optical elements635 are shown in the figure relatively close together, relativelycoplanar and relatively parallel with the platen, one or more imagersand the associated optical elements may be located at an angle relativeto the platen 210 and/or target area 212 in one embodiment. Moreover,one or more imagers may be placed in a non-coplanar configuration inanother embodiment. Also, in yet another embodiment, one or more imagersmay be configured to image light that undergoes total internalreflection at the interface of the finger 205 with the platen targetarea 212. While four imagers are shown, any number of imagers 630 may beadded to the system. Various imagers may provide distinct and/or uniqueimages of the target area under various multispectral opticalconditions.

The various imagers may image a finger 205 in the target area 212substantially simultaneously under the same illumination condition. Forexample, a while light source or sources may illuminate the finger andeach imager may record an image of the finger 205 under various opticalconditions. Simultaneous or substantially simultaneous imaging mayprovide a consistent set of images of the finger 205 that removes,mitigates, or minimizes the affect of any finger jitter, motion, ambientvariations, etc., from the various images. Thus, finger characteristicsmay correspond well from image to image. In one embodiment, theintegration time of the imagers, during which an image is recorded,overlap. In another embodiment, the imagers may image at the same time.For example, each frame imaged at a first imager may be synched with aframe at a second imager. In another embodiment, the imagers record animage within less than one second of each other. In another embodiment,the imagers record an image within less than 500 microseconds of eachother. In another embodiment, the imagers record an image within lessthan 100 microseconds of each other.

In another embodiment, the imagers may provide continuous imaging Insome embodiments, each imager is synched to image at relatively the sametime. For example, the imagers may record images with a video frame rateof 15, 30, 60, or 75 Hz. The imagers may be synched by a clocked signalfrom a processor and/or clock. If the imagers are properly synchedtogether, a single frame from each imager may be saved into memory thatis synched with the frames from the other imagers. For example, theframe may be chosen for storage based on focus, relative location of theskin site, jitter, orientation, contrast, skin site motion, lighting,ambient effects, imager effects, etc. In another embodiment, a set offrames is recorded into memory. A single synched frame may be selectedfrom each imager and used to derive a multispectral image.

The embodiments described throughout this disclosure may produce a setof images of the finger and/or hand under different optical conditionsor produce data from which such a set may be produced usingreconstruction techniques. For purposes of illustration, the followingdiscussion is made with reference to such a set of multispectral images,although it is not necessary to produce them for subsequent biometricprocessing in those embodiments that do not generate them directly. Ingeneral, the images collected by the device described in this disclosuremay differ in polarization conditions, image angle and location, as wellas spectral properties. Furthermore, in the case of a color imagercomprised of a color filter array, the color images may be extracted assubarrays of the raw pixel values or may be color-interpolated values,as known to one familiar in the art. The images from the plurality ofimagers may need to be aligned, tiled, shifted and/or otherwisepreprocessed prior to further processing. An illustrative set of alignedand processed multispectral images is shown in FIG. 10A, with the setdefining a multispectral datacube 1000.

One way to decompose the datacube 1000 is into images that correspond toeach of the multispectral conditions used to image the sample in themeasurement process. In the figure, five separate images 10005, 1010,1015, 1020, and 1025 are shown, corresponding to five discretemultispectral conditions. In an embodiment where visible light is used,the images might correspond, for example, to images generated usinglight at 450 nm, 500 nm, 550 nm, 600 nm, and 650 nm. For example, theillumination source includes a broadband white light sources and/or eachimager may include a color filter. In other embodiments the images mayrepresent polarization conditions, imaging angle, resolution, spatialmodularity, focal plane modularity, and/or TIR conditions. In someembodiments, each image may represent the optical effects of light of aparticular wavelength interacting with skin and. Due to the opticalproperties of skin and skin components that vary by wavelength,polarization, and/or angle of imaging, each of the multispectral images10005, 1010, 1015, 1020, and 1025 will be, in general, different fromthe others.

In some embodiments, each of the multispectral conditions correspond toa different wavelength or wavelengths of light. Accordingly, thedatacube may thus be expressed as R(X_(S), Y_(S), X_(I), Y_(I), λ) anddescribes the amount of diffusely reflected light of wavelength λ seenat each image point X_(I), Y_(I) when illuminated at a source pointX_(S), Y_(S). Different illumination configurations (flood, line, etc.)can be summarized by summing the point response over appropriate sourcepoint locations. A fingerprint or handprint image F(X_(I), Y_(I)) canloosely be described as the multispectral data cube for a givenwavelength, λ_(o), and summed over all source positions:

${F\left( {X_{I},Y_{I}} \right)} = {\sum\limits_{Y_{S}}{\sum\limits_{X_{S}}{{R\left( {X_{S},Y_{S},X_{I},Y_{I},\lambda_{0}} \right)}.}}}$The multiple images collected from a single acquisition event may thusbe post-processed to produce a single composite fingerprint image thatis fully compatible with conventionally collected “standards-based”legacy fingerprint databases. In addition the multispectral images maybe used to ensure that the sample has optical properties consistent witha living human finger. The composite image and the liveliness assessmentmay be reported by the analyzer 108.

Contactless Finger Sensor

A contactless biometric sensor does not include a platen that defines atarget space where illumination sources and/or imagers are focusedand/or where a sample may be placed for imaging. Instead, the imagersand/or illumination sources may be focused at a target space that isdefined within free space without definition with a platen or any otherphysical element or device. A user may place their hand and/or finger(s)within the target space without touching, contacting, and/or referencinga platen. In some embodiments the biometric system and/or device mayinclude a window between at least some of the optical elements, forexample, imagers and/or illumination sources, and the target space. Sucha window may be used to seal the optical elements for protection fromthe elements and to keep the area clean. Such a window should not beconfused with a platen and is not configured to receive a skin site.Accordingly, a finger may be placed within the target space and imagedwith one or more imagers. As discussed throughout this disclosure invarious embodiments, a contactless biometric system may use varioustechniques to provide a user an indication of the location and/or boundsof the target space. In other embodiments, the imagers singularly or incombination may employ various techniques to image a finger and/or handdepending on the relative location of the finger and/or hand to theimagers.

FIGS. 7A, 7B, 7C and 7D illustrate various views of a contactlessbiometric sensor apparatus according to one embodiment. In thisembodiment, the contactless biometric sensor includes four imagers 730,optional optical elements 735, and four illumination sources 720. Anynumber of imagers and/or illumination sources may be used. The simplestcontactless biometric sensor includes a single illumination source and asingle imager. The four imagers 730 may provide spatial modularity,multispectral modularity, focal modularity or a combination of theabove. For example, each imager 730 may image a different area of thetarget space. As another example, each imager may imager the fingerunder distinct multispectral conditions.

FIGS. 8A, 8B, 8C and 8D illustrate various views of a multispectrallymodular, contactless biometric sensor apparatus with multispectralimagers 830 that focus on different imaging planes according to oneembodiment. Various illumination elements 820 are shown. As shown in thefigure, the biometric sensor includes 16 imagers 830. In thisembodiment, four imagers 830A, 830P, 830E, 830O are focused on firstimaging plane 880, another four imagers 830D, 830M, 830F, 830N arefocused on a second imaging plane 881, another four imagers 830H, 830C,830G, 830I are focused on a third imaging plane 882, and yet anotherfour imagers 830B, 830L, 830K, 830J are focused on a fourth imagingplane 883. For the sake of clarity, the focal plane for each imager isshown for some, but not all imagers, in the figure. Each of the fourimagers focused at the same imaging plane are configured to provide animage under a different multispectral condition. Thus, the imagers maybe configured to provide the same multispectral images of the finger ateach imaging plane. While 16 imagers are shown in the figure, any numberof imagers may be used with any combination focused at different imagingplanes and/or providing different multispectral images.

FIGS. 9A, 9B, 9C and 9D illustrate various views of a spatially modular,contactless biometric sensor apparatus with imagers that focus ondifferent imaging planes according to one embodiment. Variousillumination elements 820 are shown. In this embodiment subsets of fourimagers are focused on different imaging planes as described above inregard to FIGS. 8A, 8B, 8C and 8D. However, in this embodiment each ofthe four imagers in each subset are focused on a different spatialportions of the imaging plane, thus providing spatial modularity. As canbe seen in FIG. 9C, in this embodiment, imagers 830D and 830P arefocused on different portions of imaging plane 882, and imagers 830H and830L are focused on different portions of imaging plane 883. As can beseen in FIG. 9D, in this embodiment, imager 830D is focused on imagingplane 882, imager 830C is focused on imaging plane 881, and imagers 830Aand 830B are focused on different portions of imaging plane 881.

In any embodiment, each of the imagers may be a small wafer-levelcamera. Moreover, the entire array of imagers may be provided on asingle wafer and/or circuit board. For example, such imagers may beOptiML™ wafer-level camera produced by Tessera® or the like. Variousother wafer-level cameras may also be used. In other embodiments CMOSsensors and/or CCD sensors may be used as imagers.

Various other contactless systems may be used. For example, imagers withauto focus may be used to focus light from a finger and/or hand at avarious distance from the imager. In another embodiment, an imager maybe used that provides a large depth of field. In another embodiment, animager may be used that has a large numerical aperture. In yet anotherembodiment, wavefront coding transfer functions may be used.

Spatially Modular Hand Sensor

FIGS. 11A, 11B, 11C and 11D illustrate various views of a spatiallymodular biometric hand sensor apparatus according to one embodiment. Thebiometric hand sensor, according to this embodiment includes a largeplaten 1110 with a target surface 1112 for receiving a hand 915. Aplurality of light sources 1120, optional optical elements 1135, andimagers 1130 are also included. Each imager may be focused on adifferent portion of the target surface 1112. In some embodiments, theportions of the target surface imaged by the imagers 1130 overlap and/orcover the entire target surface 1112 as shown in the figures. In otherembodiments, the portions of the target surface imaged by the imagers1130 do not overlap. In yet another embodiment, the portions of thetarget surface 1112 imaged by the imagers do not cover the entire targetsurface 1112, instead they cover only specific portions of the targetsurface. Any number of illumination sources may be used to illuminate ahand 1115 on the target surface 1112. Depending on the design and/orneeds, more or less imagers 1120 may be used to image the target surface1112. Due to the modularity of the imagers, additional imagers may beadded.

A spatially modular biometric sensor may provide images of portions ofhand 2005, 2010, 2015, 2020, 2025, 2030 according to one embodiment, asshown in FIG. 21. Each image includes a similarly sized imager of aportion of a hand. Some overlap between images may occur as shown inFIG. 20. In another embodiment, specific locations of a hand are imagedby a different imager as shown in FIG. 18. Three images are produced foreach finger. For example, the pinky (the smallest, left-most finger) isimaged in three areas 1825, 1826, 1827 corresponding to the portion ofthe finger between the knuckles or joints. The other fingers havesimilar coverage. The thumb is imaged in two areas 1825, 1836 betweenjoints. The body of the hand is imaged in three locations, thehypothenar 1830, palm core 1831, and thenar 1832. Any other combinationof images of the hand may be devised.

As shown in FIG. 19, a multispectral hand sensor, whether contactless ornot, may provide a datacube 1900 that includes images that correspond toeach of the multispectral conditions used to image the hand in themeasurement process. In the figure, five separate images 1905, 1910,1915, 1920, and 1925 are shown, corresponding to five multispectralconditions. In an embodiment where visible light is used, the imagesmight correspond, for example, to images generated using light at 450nm, 500 nm, 550 nm, 600 nm, and 650 nm. For example, each imager mayinclude a color filter. In other embodiments the images may representpolarization conditions, imaging angle, and/or TIR conditions. In someembodiments, each image may represent the optical effects of light of aparticular wavelength interacting with skin and. Due to the opticalproperties of skin and skin components that vary by wavelength,polarization, and/or angle of imaging, each of the multispectral images1905, 1910, 1915, 1920, and 1925 will be, in general, different from theothers.

FIG. 12 shows a block diagram of a biometric hand sensor systemincluding a computational device 502, such as the one shown in FIG. 5,according to one embodiment. In this embodiment, 16 imagers 510 andprocessors 515 with memory 520 are coupled to the computational device502. In another embodiment, imager memory 520 may be shared amongstimagers 515 and/or with the computational device 502.

Contactless Hand Sensor

FIGS. 13A, 13B, 13C and 13D illustrate various views of amultispectrally and/or spatially modular contactless biometric sensorapparatus according to one embodiment. In this embodiment, thecontactless biometric hand sensor includes four imagers 1330 and fourillumination sources 1320. Any number of imagers and/or illuminationsources may be used. The simplest contactless biometric hand sensorincludes a single illumination source and a single imager. The fourimagers 1330 may provide spatial modularity, multispectral modularity,focal plane modularity or a combination of the above. For example, eachimager 1330 may image a different area of the target space. As anotherexample, each imager 1330 may imager the hand under distinctmultispectral conditions. As another example, each imager 1330 may imagea different focal plane.

FIGS. 14A, 14B, 14C and 14D illustrate various views of a spatially andmultispectrally modular, contactless biometric sensor apparatusaccording to one embodiment. Sixteen imagers 1420, and sixteen optionaloptical elements 1435 are shown along with eight illumination sources1420. Any number of illuminations sources 1420 of any type may be used.Various optical elements 1435 may also be used.

FIGS. 15A, 15B, 15C and 15D illustrate various views of a spatiallyand/or multispectrally modular, contactless biometric sensor apparatuswith imagers that focus on different imaging planes according to oneembodiment. For convenience in describing these embodiments, fourimagers 1520 are shown in groups 1560 outlined by doted lines. Forexample, a first group 1560A includes imagers 1520A1, 1520A2, 1520A3,and 1520A4. Each of these imagers provides imaging coverage for a firstzone in target space corresponding to their placement in the imagerarray 1500, yet each imager 1520 is also focused on different imagingplane. Thus, the imagers 1520 within a group 1560, provide coverage fora specific lateral zone, possibly with overlap, they also providecoverage for vertical distance from the imagers by focusing at differentfocal planes. While the figure shows four imagers 1520 placed in a group1560, any number of imagers may used. Moreover, any number of groups1560 may be used as well. Due to the modular nature of the system,imagers 1520 and groups 1560 may be added as needed.

In another embodiment, each imager 1520 within a group 1560 may imagethe hand under a different multispectral condition. For example, imager1520A1 may provide an image of red light from the area of the handcorresponding to the group 1560A location in the imager array 1500.Imager 1520A2 may provide an image using a polarizer of the area of thehand corresponding to the group 1560A location in the imager array 1500.Imager 1520A3 may provide an image with a resolution of 2,000 PPI orhigher, while other imagers provide imagers with a resolution less than2,0000 PPI. Imager 1520A4 may provide an image of green light from thearea of the hand corresponding to the group 1560A location in the imagerarray 1500. Various other multispectral conditions may be used as well.Imagers within a group, according to another embodiment, are notnecessarily contiguous as shown. Moreover, in another embodiment, theplacement of the imagers 1520 within the imager array 1500 may be placedat different locations or elsewhere than within a close planar imagerarray 1500 as shown.

In another embodiment, the imager array 1500 may provide imagers 1520that provide spatial, multispectral and focal plane modularity. Forexample, the imagers may image spatial zones of a hand within the targetspace. Subset of these imagers may be focused at various focal planeswith various multispectral conditions. That is, each imager may image aspatial zone at a set focal plane using one multispectral condition.Those skilled in the art will recognize the various combinations thatcan be implemented.

Proximity Sensor User Interface

FIG. 16 shows a contactless biometric system user interface with aholographic image of a hand 1615 according to one embodiment. As shown,a number of illumination sources 1620, imagers 1630 and optical elements1635 are shown. The imagers 1630 and illumination sources 1630 areconfigured to illuminate and image a hand and/or finger placed withinthe target space 1612. Holographic image generator (not shown) isincluded that provides a holographic image of a hand 1615 within thetarget space 1612. Thus, a user may place their hand within the targetspace 1612 by placing their hand on, near, or within the holographichand image 1615. The holographic image generator may also provide avolumetric display or image. An optional structure 1640 is shown in thefigure. Other embodiments may use a holographic image of a finger ratherthan a hand.

FIG. 17 shows a contactless biometric system user interface with a lightarray 1750 according to one embodiment. As shown, a number ofillumination sources 1720, imagers 1730 and optical elements 1735 areshown. The imagers 1730 and illumination sources 1730 are configured toilluminate and image a hand and/or finger placed within the targetspace. Two light sources 1745, for example two lasers or laser diodes,each provide a light beam 1750 that at least partially defines someboundaries of the target space. Any number of light sources may be usedin any configuration. As a user moves their hand or finger into thetarget space, the user can see the light beam on their hand or fingerand know that they are approaching a boundary of the target space. Anoptional structure 1740 is shown in the figure.

Various other user interface elements may be implemented. For example,in one embodiment a proximity sensor may be implemented in conjunctionwith a speaker or other visual interface. The proximity sensor, forexample, may user stereoscopic imagers and/or stereoscopic lightsources. When the proximity sensor detects the presence of an objectwithin the target space, the illumination sources may illuminate theobject and the imagers may image the object within the target space. Anaudible interface, for example, a speaker, may also be used to alert theuser that an image has been taken, that the user's hand and/or finger iswithin the target space, and/or to ask the user to move their handand/or finger to align it within the user space.

Proximity Sensor

A proximity sensor and/or presence sensor may also be included invarious embodiments. In contactless biometric systems, it is importantto know whether a biometric feature of interest is within a targetspace. A proximity sensor may make such a determination. For example, aproximity sensor may incorporate stereoscopic imagers and/orstereoscopic illumination sources. The system may then analyze when peakintensities approach a calibrated area of an image associated with thetarget space. A stereoscopic illumination proximity sensor may includeat least two illumination sources located a distance apart form eachother and an imager placed between the two illumination sources. As anobject under illumination by such stereoscopic illumination sources,approaches the imager a graph of the peak intensities across the imagerconverge. The system may then determine whether the object is within thetarget space by making a comparison with calibrated data.

A stereoscopic proximity sensor may include at least two imagers sourceslocated a distance apart form each other and an illumination sourceplaced between the two imagers. As an object under illumination,approaches the illumination source and/or imagers, a combined graph ofthe peak intensities of the two imagers begin to converge. Moreover, asingle imager and two illumination sources may be used. Similarly, agraph of the intensity versus lateral imager position will provideconverging peaks as an object approaches the imager and/or illuminationsources. The system may determine whether an object is within the targetspace by making a comparison with calibrated data. Various otherproximity detection techniques are provided in previously incorporatedU.S. patent application Ser. No. 12/100,597.

In yet another embodiment, a light source may illuminate the targetspace with a large angle of incidence, for example, greater than 60°from the normal of the target space. The light source, in variousembodiments, may be a monochromatic blue light source or, in anotherembodiment, the light source may emit monochromatic light less thanabout 600 nm. The light source or sources illuminate not only the targetspace but also the area immediately above the target from beneath thetarget space. A color filter array filters light from the target spaceprior to the light being incident on an imager. The color filter arraymay be any color filter array described in the various embodimentsdescribed herein. The color filter array filters light according towavelength bands. Thus, the relative intensity of a wavelength band maybe compared with other wavelength bands. As a purported biometricfeature approaches the target, monochromatic light is reflected from thesurface of the biometric feature. Accordingly, the relative intensity ofthe wavelength band containing the wavelength of the monochromatic lightincreases relative to other frequency bands as the purported biometricfeature approaches the target. Accordingly, the intensity of blue lightis monitored relative to the intensity of red and/or green light. If theintensity of blue light relative to the intensity of red and/or greenlight increases, then a purported biometric feature is proximate to thetarget space. If the blue light intensity does not increase enough, thanthere is no purported biometric feature proximate to the target and thesystem continues to monitor the intensity levels of various wavelengthbands.

FIG. 22 shows a flowchart of a biometric detection using variousembodiments. While a number of steps or processes are shown, embodimentsmay include every step or process, additional steps or processes, oronly a one or more steps or processes. Moreover, each step or processmay include various sub-steps or sub-processes. At block 2205 thelocation of the target space is indicated to a user. This indication mayinclude, for example, a holographic image, light beam array, audioindications, visual indications, a platen, a prism, etc. The presence ofan object within the target space, such as a skin site, is sensed ordetected at block 2208. The presence of an object within the targetspace may be sensed using stereoscopic imagers and/or stereoscopicillumination sources and/or multispectral techniques. The skin site isilluminated at block 2210. The illumination may occur prior to any otherstep described herein and/or may occur only after the presence of a skinsite is detected. Various illumination sources may be used under anyvariety of multispectral conditions, such as, wavelength, wavelengths,polarization, angle, etc. During illumination the skin site is imagedusing two imagers at block 2215A and 2215B. These imagers may image theskin site substantially simultaneously. That is, these imagers may seethe object in multiple ways under a single illumination sequence. Anynumber of imagers may be used. The imagers may image the skin site underany variety of multispectral conditions, such as, wavelength,wavelengths, polarization, resolution, spatial modularity, focal planemodularity, imaging angle, etc. A multispectral image may be derivedfrom the images produced from the imagers at block 2220. A biometricfunction may then be performed at block 2225. The biometric function mayinclude identification of an individual, associating an individual withan access code, associating an individual with a group of individuals,determining whether access to a facility, building, resort, activity,automobile, security area, and/or device is permissible, performing aliveliness determination, performing a spoof determination, biometricmatching (identification or verification), and/or estimation ofdemographic parameters including age, gender and ethnicity, etc.

Exemplary Hardware

Various embodiments described herein use a light source to illuminate atarget area, target surface, platen, skin site, finger, hand, etc. Suchillumination sources may include a broad-band source such as anincandescent bulb, a white-light LED, a glowbar, or others of the sort.Alternatively, the illumination source may comprise one or morenarrow-band sources such as LEDs, lasers and laser diodes, quantum dots,optically filtered sources and the like. In some cases, the illuminationsystem may incorporate optical polarizers in such a way that the lightfrom one or more sources is polarized before impinging on the hand. Insome cases the polarizer may be a linear polarizer or a circularpolarizer. In some embodiments, multiple light sources are illuminatedsimultaneously during normal operation. In other cases, the multiplelight sources may be illuminated in some sequence, during which amultiplicity of images are captured and recorded. In some embodimentsmore than one illumination source is shown in a figure or described, insuch embodiments, a single light source may also be used.

Some embodiments described herein require one or more imagers. Theseimagers may comprise, for example, a silicon CMOS imager or a siliconCCD imager. Alternatively, the imager may comprise a photodiode arraymade of materials such as MCT, lead-salt, InSb, InGaAs, or a bolometerarray, or other devices and materials that enable the capture of imagescorresponding to the desired illumination wavelengths. In anotherembodiment a wafer-level imager or an array of wafer level imagers maybe used. In addition to the imaging array, there may be one or morepolarizers present in the imaging system and located such that theimager “views” the hand or a portion thereof through the polarizer. Suchpolarizers may be linear or circular polarizers. In some cases, thepolarizer in the imaging system may be arranged such that it issubstantially orthogonal or crossed relative to one or more polarizerspresent in the illumination system. In some cases, the imager polarizermay be arranged to be substantially parallel or the same orientation asthe illumination polarizer.

In cases where the imager views the hand through a polarizer that issubstantially crossed relative to the illumination polarizer, theresulting image tends to emphasize image features that lie below thesurface of the skin. In cases where the imager views the hand through apolarizer that is substantially parallel to the illumination polarizer,the resulting image tends to emphasize image features that lie at ornear the surface of the skin. In cases where either the illuminationpolarizer or image polarizer or both are omitted, the resulting imagetends to contain effects from both surface and subsurface features. Insome cases, it may be advantageous to collect and analyze imagescollected under different polarization conditions in addition to orinstead of images taken with different illumination wavelengths.

In some cases, an imager may be a color imager capable of separatingmultiple wavelength bands. The use of such a color imager may be used incases that a broad-band illumination source is used or multiple,different narrow-band illumination sources are turned on simultaneously.In such cases, information from multiple illumination conditions may becollected simultaneously, reducing the time and/or data volumerequirements of an equivalent sequential series of monochromatic images.In some cases the color imager may be obtained by combining a digitalimager with broad wavelength response with a color filter array thatprovides a narrower wavelength response to each imager pixel. In somecases the color filter array may contain three different color-selectivefilters (red, green and blue) in a Bayer pattern as known to onefamiliar in the art. Other variations of a color filter array as well asother means of color separation may also be advantageously employed.

Both the illumination and imaging systems may include other opticalcomponents such as lens, mirrors, phase plates, shutters, diffusers,band-pass optical filters, short-pass optical filters, long-pass opticalfilters, and the like in order to direct, control and focus light in amanner known to one familiar in the art.

In addition to the illumination and imaging subsystems, there may be aplaten on which the hand is placed for imaging. Alternatively, theplaten may be omitted and the hand imaged in free space.

In various embodiments, the light sources and/or illumination sourcesare white-light LEDs. There may be two banks of LEDs: one with a linearpolarizer present and one without a polarizer. Both banks of LEDsilluminate a platen through diffusers, lenses and/or mirrors to achievemoderately consistent illumination over the platen area. The platen maybe a plane glass plate. The imagers described throughout this disclosuremay be color silicon CMOS or CCD imagers, monochromatic imagers,wafer-level cameras, etc. Lenses and/or mirrors are used to image thetop surface of the platen onto the imager may also be used inembodiments described herein. A short-pass filter is placed in theimaging system to significantly reduce the sensitivity of the imager toinfrared light may be used. A linear polarizer may be placed in theimaging system such that it is substantially orthogonal to the polarizerpresent in one of the illumination banks. In other embodiments, theimaging system and number of pixels may be designed to image at aresolution of between 100 and 2,000 pixels per inch (PPI). In otherembodiments, the imaging system may be designed to image the hand with aresolution of approximately 500 PPI. A series of two images may becollected: one with the non-polarized white light illuminating the handand one with the cross-polarized light illuminating the hand.Optionally, a third image may be collected with all illumination LED'sturned off, resulting in an image that represents the effect of ambientlight. In some cases, the ambient-light image (or some grey-level scaledversion of it) may be subtracted from one or both of the illuminatedimages to produce an estimate of corresponding images in which noambient light is present.

Moreover, one or more imagers in any of the various embodiments mayinclude a high resolution imager. As noted above, a multispectral imagecan be derived from images with different resolutions. That is, imagerswith various resolutions may be used to derive a multispectral image.Such imagers may be used, for example, to image the hand(s) and/or foot(feet) of infants, including neonatal and/or premature infants. In oneembodiment, a high resolution imager may be capable of imaging at least1,000 pixels per inch (PPI). Such images may be capable of showing poresand/or the shape of ridges in a finger and/or hand or foot. In anotherembodiment, a high resolution imager may be capable of imaging at least2,000 PPI, which may show pores and/or the shape of ridges in the fingerand/or hand or foot of a neonatal or premature infant. In anotherembodiment, a high resolution imager may be capable of imaging at least3,000 PPI. In another embodiment, a high resolution imager may becapable of imaging at least 4,000 PPI.

Various embodiments may be provide identification of an individual byanalyzing an image of the individual's fingerprint, handprint and/orpalm print. Such embodiments may compare minutiae points, fingerprint,palm print and/or handprint patterns, multispectral characteristics ofan finger, hand and/or palm, etc. Other identifying features may also beused as skin discolorization, deformation, scars, marks, tattoos, moles,warts, freckles, etc. Anything within an image that may aid in thebiometric determination may be considered.

FIG. 23 shows an image of a finger 2300 with a tattoo-like feature 2310according to one embodiment. A tattoo-like feature, a tattoo, or othermarkings may aid in a biometric determination. FIG. 24 shows an image ofa hand 2400 with a number of moles 2405 and a scar 2410 according toanother embodiment. Moles 2405, scars 2410, markings, and/or otherdiscolorizations may also be used to aid in a biometric determination.Features such as tattoos, scars, and/or marks can be used as a highlyreliable differentiator between individuals.

Certain existing sensor products that use multispectral imaging usecontact as a mechanism of position registration to simplify severalaspects of the system design. Multispectral imaging fingerprinttechnology also offers the industry's best protection against spoofattempts due to the extensive information that is captured withmultispectral imaging. Such imaging yields extensive data from thesurface and the subsurface optical characteristics of the finger orspoof material from which the fingerprint is acquired that makesdifferentiating genuine from fake readily done.

The sensor described herein provides a true contactless fingerprintsensor that is fast, intuitive, and easy to use, while capturingfingerprints that are fully compatible with historical AutomatedFingerprint Identification System (“AFIS”) systems. The sensoreliminates artifacts due to finger movement and facilitates easy andreliable user interaction. this rapid acquisition capability is obtainedin one embodiment through the use of multiple imagers that aresynchronized to simultaneously capture all required images.

For example, a plurality of the imagers may be used to monitor the spaceover the sensor, which may be further actively illuminated at somewavelength or illuminated by ambient light. The plurality of imagers maybe used to detect motion in the space above the sensor and initiate asensor arming sequence when such motion is detected. The plurality ofimagers may further be used to determine the approximate location of theobject in the space above the sensor based upon the differing (parallax)views of the imagers. The images from the plurality of sensors may beanalyzed to determine when an object above the sensor is in thepreferred space to trigger the sensor acquisition. In some embodiments,the images from the plurality of imagers will also be analyzed todetermine if the object in the space above the sensor has the opticalcharacteristics of the finger and will only trigger an acquisition whenthe object is consistent with a finger and in the proper location.

In one embodiment, the illumination subsystem comprises one or morelight-emitting diodes that illuminate the region of interest above thesensor with light of the required characteristics. The light-emittingdiodes may sometimes comprise white-light emitting diodes. Alternativelyor additively, one or more of the light-emitting diodes may be anarrow-band or monochromatic light source. In cases where a plurality ofsuch light sources are used, the light sources may be substantially thesame or they may have substantially different wavelengthcharacteristics. In some cases, such light-emitting diodes may comprisesources that emit in red, green, and blue wavelengths. In some cases,one or more light-emitting diodes may emit at wavelengths other thanvisible wavelengths such as in the near ultraviolet or the nearinfrared. In any of these illumination configurations, one or moreillumination source may be linearly polarized using a sheet polarizer(not shown).

In one embodiment, the imaging system may comprise a plurality ofimagers. The imagers may be silicon arrays and may be fabricated asdigital CMOS devices or CCD devices. One or more of the imagers may bepanchromatic (“black and white”) imagers. Some of the panchromaticimagers may incorporate a wavelength filter to limit the wavelengthsthat are substantially seen by the imager. The non-limited wavelengthsmay be a portion of the visible wavelength region. Alternatively, thenon-limited wavelengths may comprise wavelengths in the near ultravioletor near infrared wavelength regions. One or more of the imagers may becolor imagers. The color imager may comprise a color filter arrayconsisting of red, green and blue pixels arranged in some pattern suchas a Bayer pattern. Alternatively, the color imager may be comprised ofan arrangement of chromatic beam splitters and multiple panchromaticimagers, as known to one familiar in the art. While the discussion belowsometimes makes specific reference to “color imagers” in providingexamples of specific embodiments, it should be understood that theseembodiments are merely exemplary and that other embodiments mayincorporate some or all of the imager variations described herewith orothers that will be obvious to one familiar in the art.

In a particular embodiment, the imaging subsystem comprises some numberof color imagers that are oriented and focused on the trigger point ofthe three-dimensional sensing subsystem. When the position sensor istriggered, all imagers will substantially simultaneously capture animage of the finger that triggered the sensor. This rapid andsubstantially simultaneous collection of multiple images will mitigatemotion artifacts and increase the overall robustness anduser-friendliness of the sensing system. Some portion of the colorimages may sometimes have optical polarizer attached to them (not shown)in order to provide the ability to capture images in a crossed-polarizedmodality.

In some embodiments, the plurality of imagers may be oriented such thatthey all substantially image a similar region above the sensor. In otherembodiments, some or all of the imagers may image different regions ofspace. In some embodiments the imaged regions may substantially overlap.In some embodiments the imagers may image different regions of spacethat are all substantially at the same focal distance or “height” abovethe sensor. In so doing, the sensor system may be able to capture abigger object field than would be possible if the same imagers werefocused on the same region of space. In some embodiments the imagers mayimage regions of space at different distances (heights) from the sensor,which enables the sensor to acquire data over a larger range of focaldistances than provided for if all imagers were focused at the samefocal distance.

Methods for obtaining a reliable and intuitive user interface arebelieved to include providing the user with a guide to properorientation and placement of a finger through the use of a hologram thatshows a hand and finger in the proper place above the sensor. This wouldpermit the user simply to place his finger in a similar position, whichwill then trigger the measurement sequence.

Thus, having described several embodiments, it will be recognized bythose of skill in the art that various modifications, alternativeconstructions, and equivalents may be used without departing from thespirit. For example, the principles described herein could be applied tofour-finger acquisition, to whole-hand imaging, or to imaging of theskin on other body parts. Accordingly, the above description should notbe taken as limiting the scope, which is defined in the followingclaims.

1. A biometric system comprising: one or more illumination sources configured to illuminate at least a portion of a target space; a first imager configured to receive light from at least a portion of the target space under a first optical condition; a second imager configured to receive light from at least a portion of the target space under a second optical condition, wherein the first optical condition is distinct from the second optical condition; and an analyzer communicatively coupled with the one or more illumination sources and the plurality of imagers, wherein the analyzer is configured to control the operation of the one or more illumination sources, the first imager, and the second imager in order to produce a multispectral image of a skin site of a purported individual placed within the target space from the light received at first imager and the second imager, wherein the analyzer is configured to derive spatially distributed multispectral characteristics from the one or more multispectral images.
 2. The biometric system according to claim 1, wherein the analyzer is configured to control the first imager and the second imager wherein the first imager and the second imager provide an image of the skin site substantially simultaneously.
 3. The biometric system according to claim 1, wherein the target space is at least partially defined by a platen.
 4. The biometric system according to claim 1, wherein the target space is adapted to receive a human hand.
 5. The biometric system according to claim 1, wherein either or both of the first imager and the second imager comprise one or more optical elements selected from the group consisting of a color filter, a color filter array, a linear polarizer, a circular polarizer, a diffuser, a collimator, a grating, and a lens.
 6. The biometric system according to claim 1, wherein the first imager is configured to receive light from a first subspace of the target space and the second imager is configured to receive light from a second subspace of the target space.
 7. The biometric system according to claim 1, wherein the first imager is focused at a first focal plane and the second imager is focused at a second focal plane, wherein the first focal plane and the second focal plane are distinct.
 8. The biometric system according to claim 1, wherein the target space is located within free space.
 9. The biometric system according to claim 1, further comprising at least a first processor coupled with the first imager and a second processor coupled with the second imager.
 10. The biometric system according to claim 1, further comprising a user interface configured to substantially indicate at least a portion of the target space to a user.
 11. The biometric system according to claim 1, further comprising a presence detector configured to detect the presence of the skin site within the target space.
 12. A method for collecting a multispectral biometric image, the method comprising: illuminating at least a portion of a target space; receiving light from at least a portion of the target space under a first optical condition; separately receiving light from at least a portion of the target space under a second optical condition substantially simultaneously as receiving light from the target space under the first optical condition, wherein the first optical condition and the second optical condition are distinct; deriving a multispectral image of a skin site of a purported individual within the target space from the light received under either or both of the first optical condition and the second optical condition; and deriving spatially distributed multispectral characteristics from the multispectral image.
 13. The method according to claim 12, further comprising providing an indication of at least a portion of the target space.
 14. The method according to claim 12, further comprising sensing the presence of the skin site within the target space.
 15. The method according to claim 12, wherein the first optical condition and the second optical condition are selected from the group consisting of polarized light, total internally reflected light, light with a specific wavelength, light within a specific wavelength band, light from a subspace within the target space, and light from a focal plane within the target space.
 16. The method according to claim 12, wherein a first imager provides a first image of at least a portion of the target space under the first optical condition and a second imager provides a second image of at least a portion of the target space under the second optical condition.
 17. The method according to claim 16, wherein first imager has a resolution greater than the resolution of the second imager.
 18. A biometric system comprising: illumination means for illuminating a target space; first imaging means for imaging at least a portion of the target space under a first optical condition and providing a first image; second imaging means for imaging at least a portion of the target space under a second optical condition distinct from the first optical condition and providing a second image; and processing means for controlling the illumination means, the first imaging means and the second imaging means, wherein the processing means is configured to derive a multispectral image of a skin site of a purported individual from the first image and the second image, the processing means further for deriving spatially distributed multispectral characteristics from the multispectral image.
 19. The biometric system according to claim 18, further comprising presence sensing means for sensing the presence of the skin site within at least a portion of the target space.
 20. The biometric system according to claim 18, wherein the first optical condition and the second optical condition is selected from the group consisting of polarized light, total internally reflected light, light with a specific wavelength, light within a specific wavelength band, light from a subspace within the target space, and light from a focal plane within the target space.
 21. The biometric system according to claim 18, further comprising indication means for indicating at least a portion of the target space to a user.
 22. A biometric system comprising: one or more illumination sources configured to illuminate a target space; a plurality of imagers configured to receive light from the target space under multispectral conditions, wherein each imager is configured to receive light from a different subspace of said target space; and an analyzer communicatively coupled with the one or more illumination sources and the plurality of imagers, the analyzer configured to control the operation of the one or more illumination sources and the plurality of imagers in order to produce one or more multispectral image of a skin site of a purported individual placed within the target space from the light received at any or all the imagers, wherein the analyzer includes instructions to derive spatially distributed multispectral characteristics from the multispectral image.
 23. The biometric system according to claim 22, wherein the analyzer is further configured to control the imagers such that the imagers simultaneously receive light from the target space under multispectral conditions.
 24. The biometric system according to claim 22, wherein the plurality of imagers are arranged substantially coplanar.
 25. The biometric system according to claim 22, wherein the plurality of imagers include at least one wafer-level camera.
 26. The biometric system according to claim 22, wherein the analyzer further comprises a plurality of processors, wherein each of the plurality of imagers are coupled with at least one processor.
 27. The biometric system according to claim 22, wherein the target space is adapted to receive a human hand.
 28. The biometric system according to claim 22, wherein a first subset of the plurality of imagers is focused on a first focal plane and a second subset of the plurality of imagers is focused on a second focal plane.
 29. The biometric system according to claim 22, wherein the one or more imagers receive light at a plurality of discrete wavelengths.
 30. The biometric system according to claim 22, wherein the one or more illumination sources provide light at a plurality of distinct wavelengths.
 31. The biometric system according to claim 22, wherein the target space is not defined by a platen.
 32. A biometric system comprising: one or more illumination sources configured to illuminate a target space; a first imager that receives light from a first subspace of said target space under multispectral conditions; a second imager that receives light from a second subspace of said target space under multispectral conditions, wherein the first imager and the second imager receive light substantially simultaneously; and an analyzer communicatively coupled with the one or more illumination sources, the first imager, and the second imager, the analyzer configured to control the operation of the one or more illumination sources, the first imager, and the second imager in order to derive a multispectral image of a skin site of a purported individual placed within the target space from light received at either or both of the first imager and the second imager, wherein the analyzer includes instructions to derive spatially distributed multispectral characteristics from the multispectral image.
 33. The biometric system according to claim 32, wherein said target space is defined in part by a platen.
 34. The biometric system according to claim 32, wherein said target space is configured to receive a human hand.
 35. The biometric system according to claim 32, wherein the first subspace and the second subspace comprise substantially the same subspace.
 36. The biometric system according to claim 32, wherein the first subspace and the second subspace overlap.
 37. The biometric system according to claim 32, wherein either or both of the first imager and the second imager comprise one or more optical element selected from the list consisting of color filters, color filter arrays, polarizers, diffusers, collimators, gratings, and lenses.
 38. A method for collecting a biometric image comprising: illuminating a target space with one or more illumination sources; receiving light from a first subspace of said target space with a first imager; receiving light from a second subspace of said target space with a second imager; deriving a multispectral image of at least a portion of a skin site of a purported individual within said target space from the light received at either or both of the first imager and the second imager; and deriving spatially distributed multispectral characteristics from the multispectral image.
 39. The method according to claim 38, further comprising performing a biometric function with the multispectral image.
 40. The method according to claim 38, further comprising performing a liveliness function with the multispectral image.
 41. The method according to claim 38, further comprising performing a spoof-detection function with the multispectral image.
 42. The method according to claim 38, wherein the receiving light from a first subspace of said target space with a first imager and the receiving light from a second subspace of said target space with a second imager occur substantially simultaneously.
 43. The method according to claim 38, further comprising providing a user interface configured to substantially define at least portions of the target space.
 44. A biometric system comprising: a platen adapted for placement of a purported skin site by an individual; one or more illumination sources configured to illuminate the skin site; a first imager configured to receive light from a first zone of said skin site under multispectral conditions; a second imager configured to receive light from a second zone of said skin site under multispectral conditions; and an analyzer communicatively coupled with the one or more illumination sources, the first imager, and the second imager, the analyzer configured to control the operation of the one or more illumination sources, the first imager, and the second imager in order to derive a multispectral image of the skin site from light received at either or both of the first imager and the second imager, wherein the analyzer includes instructions to derive spatially distributed multispectral characteristics from the multispectral image.
 45. The biometric system according to claim 44, further comprising at least a first processor coupled with the first imager and a second processor coupled with the second imager.
 46. The biometric system according to claim 44, wherein the analyzer included instructions to substantially simultaneously record images of the skin site with the first imager and the second imager.
 47. The biometric system according to claim 44, wherein the first imager and the second imager may include a wafer-level camera.
 48. A biometric system comprising: one or more illumination sources configured to illuminate a target space; a plurality of imagers configured to receive light from the target space under multispectral conditions, wherein at least one imager receives light with a multispectral condition distinct from the multispectral condition received with at least one other imager; an analyzer communicatively coupled with the one or more illumination sources and the plurality of imagers, wherein the analyzer is configured to control the operation of the one or more illumination sources and the plurality of imagers in order to produce a multispectral image of a skin site of a purported individual placed within the target space from the light received at any or all the imagers, wherein the analyzer includes instructions to derive spatially distributed multispectral characteristics from the multispectral image.
 49. The biometric system according to claim 48, wherein a multispectral condition is selected from the groups consisting of: polarization, illumination angle, imaging angle, illumination wavelength or wavelengths, and imaging wavelength or wavelength.
 50. The biometric system according to claim 48, wherein at least on imager of the plurality of imagers includes at least an optical element selected from the group consisting of: a color filter, a color filter array, a polarizer, a diffuser, a collimator, a grating, and a lens.
 51. The biometric system according to claim 48, wherein the analyzer includes instructions to substantially simultaneously record images of the skin site with at least two of the plurality of imagers.
 52. The biometric system according to claim 48, further comprising a plurality of processors, wherein each imager of the plurality of imagers is coupled with one of the plurality of processors.
 53. A biometric system comprising: one or more illumination sources configured to illuminate a target space; a first imager configured to receive light from said target space under a first optical condition; a second imager configured to receive light from said target space under a second optical condition; and an analyzer communicatively coupled with the one or more illumination sources, the first imager, and the second imager, the analyzer configured to control the operation of the one or more illumination sources, the first imager, and the second imager in order to derive a multispectral image of a skin site of a purported individual placed within the target space from light received at either or both of the first imager and the second imager, wherein the analyzer includes instructions to derive spatially distributed multispectral characteristics from the multispectral image.
 54. The biometric system according to claim 53, wherein the difference between the first optical condition and the second optical condition is selected from the group consisting of: a difference in polarization, a difference in illumination angle, a difference in imaging angle, a difference in illumination wavelength or wavelengths, and a difference in imaging wavelength or wavelength(s).
 55. The biometric system according to claim 53, further comprising at least a first processor coupled with the first imager and second processor coupled with the second imager.
 56. A method for collecting a biometric image comprising: illuminating a target space; receiving light from said target space under a first optical condition; receiving light from said target space under a second optical condition; deriving a multispectral image of a skin site of a purported individual within said target space from the light received at either or both of the first imager and the second imager; and deriving spatially distributed multispectral characteristics from the multispectral image.
 57. The method according to claim 56, wherein the target space is exists in free space.
 58. The method according to claim 56, wherein the difference between the first optical condition and the second optical condition are selected from the group consisting of: a difference in polarization, a difference in illumination angle, a difference in imaging angle, a difference in illumination wavelength or wavelengths, and a difference in imaging wavelength or wavelengths.
 59. The method according to claim 56, further comprising performing a biometric function with the multispectral image.
 60. The method according to claim 56, further comprising performing a liveliness function with the multispectral image.
 61. The method according to claim 56, further comprising performing a spoof-detection function with the multispectral image.
 62. The method according to claim 56, wherein the receiving light from said target space under a first optical condition and the receiving light from said target space under a second optical condition occur substantially simultaneously.
 63. The method according to claim 56, further comprising providing a user interface configured to substantially define at least portions of the target space.
 64. A contactless biometric system comprising: one or more illumination sources configured to illuminate a target space located in free space; one or more imagers configured to collect light from at least a portion of the target space under multispectral conditions; an analyzer communicatively coupled with the one or more illumination sources and the one or more imagers, the analyzer configured to control the operation of the one or more illumination sources and the one or more imagers in order to derive a multispectral image of a skin site of a purported individual placed within the target space and imaged by the one or more imagers, wherein the analyzer includes instructions to derive spatially distributed multispectral characteristics from the multispectral image.
 65. The contactless biometric system according to claim 64, wherein the target space is dimensioned to receive a human hand.
 66. The contactless biometric system according to claim 64, further comprising a user interface configured to substantially delineate the relative dimension of portions of the target space within free space.
 67. The contactless biometric system according to claim 64, further comprising a user interface configured to display a holographic image of hand within the target space.
 68. The contactless biometric system according to claim 64, further comprising a user interface that includes one or more light sources configured to illuminate portions of the skin site when the skin site is placed within the target space.
 69. The contactless biometric system according to claim 64, further comprising a user interface that includes a speaker that provides an audible indication when the skin site is placed substantially within the target space.
 70. The contactless biometric system according to claim 64, wherein the one or more imagers includes at least a first imager and a second imager, wherein the first imager is focused at a first focal plane within the target space and the second imager is focused at a second focal plane within the target space distinct from the first focal plane.
 71. The contactless biometric system according to claim 64, wherein at least one of the plurality of imagers includes an auto focus.
 72. The contactless biometric system according to claim 64, wherein at least one of the plurality of imagers includes a low numerical aperture.
 73. The contactless biometric system according to claim 64, wherein at least two of the plurality of imagers collect light from at least a portion of the target space substantially simultaneously.
 74. The contactless biometric system according to claim 64, wherein at least two of the plurality of imagers collect light from substantially the same portions of the target space under distinct multispectral conditions.
 75. The contactless biometric system according to claim 64, wherein at least two of the plurality of imagers collect light from substantially distinct portions of the target space.
 76. A method for collecting a biometric image comprising: detecting the presence of a skin site of a purported individual within a target space located in free space; illuminating the skin site within the target space with one or more illumination sources; receiving light from the target space at one or more imagers under multispectral conditions; deriving a multispectral image of the skin site within said target space from the light received at the one or more imagers; and deriving spatially distributed multispectral characteristics from the multispectral image.
 77. The method according to claim 76, further comprising providing a visual indication of portions of the target space within free space.
 78. The method according to claim 76, further comprising providing a holographic image of a hand positioned substantially within the target space.
 79. The method according to claim 76, further comprising providing an indication when the skin site is detected within the target space, wherein the indication is either or both of an audible indication and a visual indication.
 80. The method according to claim 76, determining the identity of an individual from the multispectral image.
 81. A contactless biometric system comprising: an illumination subsystem disposed to illuminate a predetermined spatial location in free space; an imaging subsystem disposed to collect light emanating from the predetermined spatial location; sensing means for sensing when a purported skin site is placed substantially within the predetermined spatial location; and an analyzer in communication with the illumination subsystem, the imaging subsystem, and the sensing subsystem, wherein the analyzer comprises instructions to operate the illumination subsystem, the imaging subsystem, and the sensing subsystem to derive a multispectral image of a skin site of a purported individual placed within the target space and imaged by the one or more imagers, wherein the sensing means includes at least one imager and a color filter array with a plurality of color mosaics, wherein each pixel of the imager corresponds to one of the plurality of color mosaics such that each pixel detects light associated with the corresponding color, and wherein the analyzer includes instructions to monitor the levels of blue light received at the imager through the color filter array and compute a mathematical function on the levels of blue light in proportion with levels of other light.
 82. The contactless biometric system according to claim 81, wherein the sensing means and the imaging subsystem comprise a single subsystem.
 83. The contactless biometric system according to claim 81, wherein the sensing means includes stereoscopic imagers.
 84. The contactless biometric system according to claim 81, wherein the sensing means includes stereoscopic illuminators.
 85. The contactless biometric system according to claim 81, wherein the color filter array is a Bayer filter array.
 86. The contactless biometric system according to claim 81, wherein the imaging subsystem comprises at least a first imager and a second imager configured to image light from the predetermined spatial location substantially simultaneously.
 87. A biometric system comprising: one or more illumination sources configured to illuminate a target space located in free space; one or more imagers configured to collect light from at least a portion of the target space under multispectral conditions; a user interface configured to communicate the proximate location of the target space in free space; and an analyzer communicatively coupled with the one or more illumination sources and the one or more imagers, the analyzer includes instructions to illuminate the target space with the one or more illumination sources, and derive a multispectral image of a skin site of a purported individual placed within the target space and imaged by the one or more imagers, wherein the analyzer includes instructions to derive spatially distributed multispectral characteristics from the multispectral image.
 88. The biometric system according to claim 87, further comprising sensing means includes stereoscopic imagers.
 89. The biometric system according to claim 87, wherein the sensing means for sensing when a purported skin site is placed substantially within the target space.
 90. The biometric system according to claim 87, wherein the user interface is configured to display a holographic image of hand within the target space.
 91. The biometric system according to claim 87, wherein the user interface includes one or more light sources configured to illuminate portions of the skin site when the skin site is placed within the target space.
 92. A method for collecting a biometric image comprising: providing an indication of the proximate location of a target space in free space; illuminating a skin site of a purported individual within the target space with one or more illumination sources; receiving light from the target space at one or more imagers under multispectral conditions; deriving a multispectral image of the skin site within said target space from the light received at the one or more imagers; and deriving spatially distributed multispectral characteristics from the multispectral image.
 93. The method according to claim 92, further comprising performing a biometric function with the multispectral image.
 94. The method according to claim 92, wherein the providing the an indication of the proximate location of a target space in free space includes providing a at least a portion of a holographic image of a hand within the target space.
 95. The method according to claim 92, wherein the providing the an indication of the proximate location of a target space in free space includes providing a at least a portion of a holographic image of a finger within the target space.
 96. The method according to claim 92, wherein the providing the an indication of the proximate location of a target space in free space includes illuminating at least portions of the target space.
 97. The method according to claim 92, wherein the providing the an indication of the proximate location of a target space in free space includes illuminating portions of the skin site when the skin site is placed within the target space.
 98. The method according to claim 92, further comprises providing an audible indication when the skin site is at least partially within the target space.
 99. The method according to claim 92, further comprises providing a visual indication when the skin site is at least partially within the target space.
 100. A biometric system comprising: conveying means for conveying an indication of the proximate location of a target space in free space; illuminating means for illuminating at least a portion of the target space; imaging means for receiving light from the target space under multispectral conditions; logic means for deriving a multispectral image of a skin site of a purported individual within said target space from the light received by the imaging means, the logic means further for deriving spatially distributed multispectral characteristics from the multispectral image.
 101. A biometric system comprising: a platen configured to receive a human hand; one or more illumination sources configured to illuminate a hand placed on the platen; a first imager configured to receive light from a first portion of the hand under multispectral conditions; a second imager configured to receive light from a second portion of the hand under multispectral conditions; and an analyzer communicatively coupled with the one or more illumination sources, the first imager, and the second imager, the analyzer configured to control the operation of the one or more illumination sources, the first imager, and the second imager in order to derive a multispectral image of the first portion of the hand from light received at first imager and derive a multispectral image of the second portion of the hand from light received at second imager, wherein the analyzer includes instructions to derive spatially distributed multispectral characteristics from the multispectral image.
 102. The biometric system according to claim 101, wherein the first imager and the second imager analyze different characteristics of the hand.
 103. A biometric system comprising: one or more illumination sources configured to illuminate a hand placed substantially within target space in free space; a plurality of imagers configured to receive light from portions of a hand placed substantially within the target space under multispectral conditions; an analyzer communicatively coupled with the one or more illumination sources and the plurality of imagers, the analyzer configured to control the operation of the one or more illumination sources and the plurality of imagers in order to derive a multispectral image of the portions of the hand from light received at the plurality of imagers, wherein the analyzer includes instructions to derive spatially distributed multispectral characteristics from the multispectral image.
 104. The biometric system according to claim 103, wherein the target space is bounded at least in part by a platen such that a hand may rest substantially on the platen.
 105. The biometric system according to claim 103, wherein the plurality of imagers include a first imager and a second imager, the first imager is focused on a first portion of a hand, and the second imager is focused on a second portion of a hand.
 106. A method for collecting a biometric image of a hand comprising: providing a target space located in free space for the placement of a human hand by an individual; illuminating a hand within the target space using one or more illumination sources; receiving light from the hand under multispectral conditions using one or more imagers; deriving at least one multispectral image of at least one portion of the hand within the target space from the received light; and deriving spatially distributed multispectral characteristics from the multispectral image. 